An inquiry into child sex abuse by Church of England clergy in Chichester has found many children suffered "abiding hurt and damage" because local safeguarding measures had fallen "woefully short" for two decades.

The inquiry by the Archbishop of Canterbury's office concluded that the West Sussex diocese has "an appalling history" of child protection failures, with "fresh and disturbing" allegations continuing to emerge.

Lambeth Palace will now oversee clergy appointments and the protection of children and vulnerable adults in the diocese amid concerns that safeguarding procedures remain "dysfunctional".

The archbishop, Rowan Williams, who set up the investigation, said the interim report "confirms that there have been many and longstanding failures in implementing a robust and credible safeguarding policy in the diocese of Chichester".

Bishop John Gladwin and Chancellor Rupert Bursell QC, who are leading the inquiry, wrote: "It has been particularly distressing to us to have met people whose lives have been deeply wounded by the abuse they have suffered at the hands of clergy and of lay people holding positions of responsibility in the Church. Sadly, these wounds often refuse to heal.

"It is clear to us that many lives have been blighted. Some have sought justice through the courts of law. Clergy have gone to prison for their abuse of children. We are clear that those who have sought justice through the courts are but the tip of the iceberg."

The report said the abuse was made worse by the "very slow" way the diocese recognised concerns and failed to act with "rigour and expedition".

"A whole series of investigations and reports across nearly two decades bears witness to a profoundly unhelpful and negative culture in parts of the diocese that led to its failure to take the action needed.

"Fresh allegations have been made and are being pursued by the relevant authorities and new people are coming forward to tell the sad story of their own abuse at the hands of clergy and other people in positions of authority in the church."

Gladwin said the problems had not only been caused by "priests who abuse" but also the culture and practice of the diocese.

The inquiry found that although it is national Church policy that every cleric should have a Criminal Records Bureau (CRB) check at least every five years, on 14 June there were 138 clergy in the diocese without up-to-date clearance.

The report, believed to be the first of its kind in the Church of England for over a century, calls for "a radical change of culture in the diocese – one in which the sanctity, dignity and well being of children and vulnerable adults is openly and transparently at its heart".

Three local priests have been charged this year with child sex offences.

The report is believed to be the first of its kind in the Church of England for more than a century.

In May last year, a review found serious failings in the senior clergy after two priests were allowed to continue working despite being accused of serious child abuse offences.

Colin Pritchard was the vicar of St Barnabas in Bexhill-on-Sea, East Sussex, until 2007, despite having been first reported to police over sex offences 10 years earlier. He was later jailed for sexually abusing two young boys.

One of the boys was also abused by Roy Cotton, who worked as a parish priest in Brede near Rye, but prosecutors decided there was not enough evidence to charge him before he died in September 2006.

Dr Williams apologised and paid tribute to the victims of the abuse.

He said: "The abiding hurt and damage done to them is something that none of us in the Church can ignore, and I am deeply sorry that they should have been let down by those they ought to have been able to trust."

The reports recommendations will also be considered by the Church of England's national safeguarding group to assess the need for any changes to its policies or the law.